1. Field of the Invention
The present invention relates to a magnetic disk device that performs magnetic recording by generating a magnetic field using electric current on a light-irradiated surface of a recording medium.
2. Description of the Related Art
Recently, a heat-assisted magnetic recording method is increasingly used as a technology that enables high density magnetic recording. The heat-assisted magnetic recording method carries out magnetic recording on a magnetic recording medium that is highly retentive to thermal fluctuation. In the heat-assisted magnetic recording method, light is focused on a surface of the magnetic recording medium to increase the temperature of the magnetic recording medium in phases, and a portion that undergoes increase in the temperature is exposed to a magnetic field to carry out magnetic recording. In the heat-assisted magnetic recording method, although exposing the recording medium to the light increases the temperature of the recording medium, the recording medium needs to be immediately exposed to the magnetic field to prevent thermal fluctuation.
For example, a data recording head which includes a magnetic field generating element and a heat generating unit are disclosed as a technology of the heat-assisted magnetic recording method in Japanese Patent Laid-Open Publication No 2004-303299. The magnetic field generating element passes electricity through a metal plate including a constrictor that constricts the electric current, and generates a magnetic field to carry out magnetic recording. The heat generating unit generates heat on the metal surface by exposing the constrictor to a laser beam from below.
However, in the conventional technology, manufacturing and especially narrowing of the metal constrictor is minute and difficult. Moreover, a separate reading head needs to be attached with great precision for using a magnetic reading head to play the magnetic recording medium. Thus, a magnetic recording head cannot be manufactured easily (for example, manufactured by using a wafer process).